A relay station is conventionally used in wireless communication systems. Relay stations include non-regenerating types that amplify and transmit received signals, and regenerating types that amplify and transmit received signals after first decoding the signal and regenerating the original data. Among mobile communication systems, a system is known that can determine communication paths capable of realizing high speed communication by multi-hop. For example, a mobile communication system includes a communication path determining unit that based on the interference level of the signals respectively received by a relay station and a base station, which form a communication path between communicating stations, determines a communication path that offers the fastest communication speed or that satisfies a specified line quality (see, for example, International Publication Pamphlet No. 2003/101132). Further, a system is known that increases the effective area of a spread spectrum-based wireless network as well as communication capacity. For example, the system has a wireless communication network that is expanded by a low-cost, channel selector-type relay apparatus capable of relaying desired signals alone (see, for example, Published Japanese-Translation of PCT Application, Publication No. 2006-501759).
With conventional regenerating type relay stations, since signals subject to amplification can be controlled according to user, the source of interference can be controlled. However, since the decoding process takes time, regenerating type relay stations have a problem in that a greater delay occurs that with non-regenerating type relay station. Meanwhile, with conventional non-regenerating type relay stations a problem arises in that since amplification is performed at a constant gain factor, the relay station may become a source of interference.